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91.
Benzene extractable aliphatic hydrocarbons from the New Albany Shale in the Illinois Basin were characterized by gas chromatography and mass spectrometry, and the total organic matter of the shale was characterized by solid state carbon-13 cross polarization magic angle spinning nuclear magnetic resonance. Core samples from a northwest-trending cross-section of the Illinois Basin were studied. Gas chromatography (GC) and gas chromatography-mass spectrometric analysis (GC/MS) data indicate a regional variation of the aliphatic composition of the shale extracts. A positive, linear relationship between the two ratios, pristane/n-C17 and phytane/n-C18, is indicated. The NMR results indicated that organic matter deposited in northwestern Illinois shale is relatively high in aliphatic hydrocarbon content while, in contrast, organic matter found in southeastern Illinois shale is relatively low in aliphatic hydrocarbon content. Our findings suggest that the organic variation of the shale is mainly due to the differences in thermal maturity of the shale organic matter and the use of pristane/n-C17 ratio as a thermal parameter in the study of oil may be extended to the study of the ancient sediments. 相似文献
92.
The propagation of spiral density waves in a differentially rotating, self-gravitating, magnetoactive and highly flattened disk is investigated by using the asymptotic theory for tightly wound spirals developed by Lin and his collaborators. We adopt the continuum fluid model as the primary basis, and our treatment will be largely analytical. The disk plasma is studied in the frozen field approximation and inhomogenceous magnetic fields in the plane of the disk are considered in detail.In a differentially rotating disk with strong magnetic fields, the field lines will be considerably distorted and the mutual influence of magnetic fields and differential rotation is by no means obvious.In this paper we present a new asymptotic dispersion relation for tightly wound spiral density waves with magnetic fields along the spiral armsB
(r). The effects of the magnetic fields lead to such terms likek
2(a
2 +V
A
2
), wherek is the wave number,a represents the speed of sound,V
A = (B
2/4)1/2 is the Alfvén speed,B denotes the field strength, and is the plasma density. These terms depict the well-known magnetoacoustic waves and could have been anticipated without a detailed computation. However the interaction of magnetic fields and differential rotation may give rise to other significant terms which are not so easy to foresee.We also present a more exact local dispersion relation by using the WKB approximation and study the effects of magnetic fields on the growth rate through the parametersQ andJ defined in the literature.Although the effects of the magnetic fields are rather insignificant for applications to Galactic dynamics, the effects of the magnetic fields are important for applications to star formation and problems related to the solar nebula. 相似文献
93.
基于PALSAR数据的青藏高原冻土形变检测方法研究 总被引:1,自引:0,他引:1
季节性冻胀和融沉导致的地面形变是青藏高原冻土区建设施工与维护的主要问题。对冻融造成的形变进行有效监测是青藏铁
路建设与维护的前提。差分干涉测量技术是地表形变监测的重要手段之一,PALSAR(L波段的合成孔径雷达)数据在非城市区域具
有较高的相关性,适合青藏高原冻土区的地表形变监测。本文选用4景覆盖研究区域的PALSAR数据,研究利用该数据进行冻土形变
检测的方法,并对其检测结果进行了分析。结果表明,该方法与水准测量方法有较好的一致性。 相似文献
94.
The typical loess on high slopes along the BaoLan High-speed Rail, China, was selected as the research object. The influence of the freeze-thaw cycle and dry-wet alternation on the shear-strength parameters of the unsaturated loess was investigated by laboratory experimental methods. Moreover, the temperature field, seepage field, and stability of slopes with different gradients were simulated under the effect of the freeze-thaw cycle and dry-wet alternation by using the geotechnical analysis software Geo-Studio. The research results showed(1) when the freeze-thaw cycle was repeated on the slope, with the frozen depth increasing, the melted depth did the same; besides, the closed loop of isotherms formed on the slope;(2) under the action of dry-wet circulation, the negative pore-water pressure and volumetric water content showed an upward tendency. However, owing to the different slope gradients, rainfall infiltration was not the same. As time went by, the differences of the negative pore-water pressure and volumetric water content between the slopes of different gradients continued to increase;(3) with the freeze-thaw cycle and dry-wet alternation increasing, the slope-safety factor decreased. Especially in the early period, the slope-safety factor changed remarkably. For slopes undergoing freeze-thaw action, the slope-safety factor was negatively correlated with the gradient. However, with regard to slopes undergoing dry-wet alternation, the result became more complex because the slope-safety factor was related to both seepage strength and slope grade. Accordingly, further research is needed to study the effect of seepage strength and slope grade on the stability of loess slopes. 相似文献
95.
Seasonal and interannual variability of carbon cycle in South China Sea: A three-dimensional physical-biogeochemical modeling study 总被引:5,自引:1,他引:4
Fei Chai Guimei Liu Huijie Xue Lei Shi Yi Chao Chun-Mao Tseng Wen-Chen Chou Kon-Kee Liu 《Journal of Oceanography》2009,65(5):703-720
The South China Sea (SCS) exhibits strong variations on seasonal to interannual time scale, and the changing Southeast Asian
Monsoon has direct impacts on the nutrients and phytoplankton dynamics, as well as the carbon cycle. A Pacific basin-wide
physical-biogeochemical model has been developed and used to investigate the physical variations, ecosystem responses, and
carbon cycle consequences. The Pacific basin-wide circulation model, based on the Regional Ocean Model Systems (ROMS) with
a 50-km spatial resolution, is driven with daily air-sea fluxes derived from the National Centers for Environmental Prediction
(NCEP) reanalysis between 1990 and 2004. The biogeochemical processes are simulated with the Carbon, Si(OH)4, Nitrogen Ecosystem (CoSINE) model consisting of multiple nutrients and plankton functional groups and detailed carbon cycle
dynamics. The ROMS-CoSINE model is capable of reproducing many observed features and their variability over the same period
at the SouthEast Asian Time-series Study (SEATS) station in the SCS. The integrated air-sea CO2 flux over the entire SCS reveals a strong seasonal cycle, serving as a source of CO2 to the atmosphere in spring, summer and autumn, but acting as a sink of CO2 for the atmosphere in winter. The annual mean sea-to-air CO2 flux averaged over the entire SCS is +0.33 moles CO2 m−2year−1, which indicates that the SCS is a weak source of CO2 to the atmosphere. Temperature has a stronger influence on the seasonal variation of pCO2 than biological activity, and is thus the dominant factor controlling the oceanic pCO2 in the SCS. The water temperature, seasonal upwelling and Kuroshio intrusion determine the pCO2 differences at coast of Vietnam and the northwestern region of the Luzon Island. The inverse relationship between the interannual
variability of Chl-a in summer near the coast of Vietnam and NINO3 SST (Sea Surface Temperature) index in January implies that the carbon cycle and primary productivity in the SCS is teleconnected
to the Pacific-East Asian large-scale climatic variability. 相似文献
96.
注浆管表面的固体润滑涂层研究 总被引:1,自引:0,他引:1
研究了帷幕灌浆中注浆管表面的固体润滑涂层组成.用附着力试验仪、耐磨试验机、冲击试验机、电子万能试验机测试了固体润滑涂层的附着力、耐磨性、抗冲击性和拔管摩擦阻力,用傅立叶红外光谱仪(FTIR)分析了固体润滑涂料磨损前后的变化.结果表明:环氧树脂固体润滑涂层的耐磨性和附着力优于不饱和树脂固体润滑涂层,但抗冲击强度低于不饱和树脂固体润滑涂层;涂敷不饱和树脂固体润滑涂层注浆管的拔管摩擦阻力小于涂敷环氧树脂固体润滑涂层注浆管的拔管摩擦阻力,比未涂敷固体润滑涂层注浆管的拔管摩擦阻力平均降低25%;耐磨性和拔管摩擦阻力随固体润滑涂层的涂层厚度增大而下降.傅立叶红外分析结果表明,涂层磨损后,部分官能团的峰面积发生了变化.试验分析表明,润滑摩擦作用机制是层剥落磨损. 相似文献
97.
圆尾斗鱼的胚胎和仔鱼发育的研究 总被引:7,自引:0,他引:7
圆尾斗鱼的受精卵呈圆球形,光滑,略带淡黄色,浮性;卵膜吸水膨胀后的平均直径为1.19mm,当水温21-23.5℃时,从受精卵到孵化出膜需42.5小时;水温22-24.5℃时,刚出膜仔鱼到卵黄囊消失需4天,到油球消失约25天。出膜30天仔鱼的形态基本与成体相似。 相似文献
98.
Jérôme Harlay Caroline De Bodt Anja Engel Sandra Jansen Quentin d’Hoop Judith Piontek Nicolas Van Oostende Steve Groom Koen Sabbe Lei Chou 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(8):1251-1265
The distribution of transparent exopolymer particles (TEP) was investigated during a coccolithophorid bloom in the northern Bay of Biscay (North Atlantic Ocean) in early June 2006. MODIS chlorophyll-a (Chl-a) and reflectance images before and during the cruise were used to localize areas of important biological activity and high reflectance (HR). TEP profiles along the continental margin, determined using microscopic (TEPmicro) and colorimetric (TEPcolor) methods, showed abundant (6.1×106–4.4×107 L?1) and relatively small (0.5–20 μm) particles, leading to a low total volume fraction (0.05–2.2 ppm) of TEPmicro and similar vertical profiles of TEPcolor. Estimates of carbon content in TEP (TEP-C) derived from the microscopic approach yielded surface concentration of 1.50 μmol C L?1. The contribution of TEP-C to particulate organic carbon (POC) was estimated to be 12% (molar C ratio) during this survey. Our results suggest that TEP formation is a probable first step to rapid and efficient export of C during declining coccolithophorid blooms. 相似文献
99.
We use five-day helioseimic data from the Taiwan Oscillation Network to study the flow around a sunspot, NOAA 7887. The p-mode oscillations in an annular region centered at the sunspot are decomposed into the modes propagating toward and away from the sunspot. We find that the frequency of an outgoing mode is greater than that of the corresponding incoming mode. This indicates that the plasma is flowing outward from the sunspot. The outflow velocity is estimated to be about 40–80 m s-1. 相似文献
100.
Yung-Ping Chou 《Solar physics》2001,199(2):345-369
We perform numerical simulations using an avalanche model for solar flares, in which the effect of avalanche event duration is included and the lateral boundary condition can be either open or periodic. The results from the simulations show that self-organized criticality (SOC) exists under a variety of conditions of helicity dissipation, and they are similar in the sense that the indices of power-law distributions of avalanche sizes are the same, while the duration and waiting time distributions differ little. Of interest are: (1) if there exists helicity dissipation in the course of avalanches, SOC exists only when the amount of helicity dissipation per avalanche is small; (2) sudden reductions in the total helicity of the system do not severely disturb SOC, if the amount reduced is moderate; (3) the distribution of waiting times is shown to be exponential, in consistent with the Poisson statistics other avalanche models have predicted, and the exponent increases as the effect of event duration becomes larger. The self-similar structure of the avalanche time series is also examined. These results imply that, although helicity is dissipated in resistive diffusion of flares, the amount of dissipation should be small and the conservation law of helicity thus holds in an approximate sense. Also, the coronal mass ejections (CMEs), observed to take helicity out of the solar corona in an eruptive way, may disrupt the statistical equilibrium of the corona only temporarily. 相似文献